Technical Field
The present invention relates to the technical field of blood-glucose testing, and more particularly, to a control method and system for test strip electrodes.
Description of Related Art
Referring to FIG. 1, the blood-glucose test strip has three electrodes: a working electrode W, a background electrode B, and a reference electrode R, arranged into an inverted triangle. In an optimized arrangement, the background electrode B and the reference electrode R are placed at the base angles, respectively, of the inverted triangle while the working electrode W is placed at the vertex.
In testing the blood-glucose of blood samples in a blood glucose test strip with a glucose meter, the three electrodes have their own functions. The reference electrode can be grounded with the voltage of 0 V. The working electrode W and the background electrode B can be applied with different working voltages. A circuit can be formed between the reference electrode R and the working electrode W to generate testing current signals. A circuit can be formed between the background electrode B and the reference electrode R to generate correcting current signals, which are used for correcting the testing current signals. Corrected testing current signals can be subsequently used to obtain the content of the blood glucose in the blood samples.
However, the test strip has such an extra wide sampling opening that blood samples can enter the reaction chamber from any part of the front side of the test strip. As such, blood samples may contact the background electrode B first or may contact the reference electrode R first. Thus, testing current signals will be affected by the direction of sampling due to the randomness of sample application Specifically, referring to FIG. 2, if a blood sample contracts the background electrode B (e.g. the sample is introduced from the left), neither electrode generates current signals when the background electrode B is covered but the reference electrode R is not in contract with the blood sample. As well, when the reference electrode R contacts the blood sample, detection signals and correcting signals are generated at the same time, and the intensity of the two signals can depend on the extent to which the reference electrode R is covered by the blood sample, so the intensity of the two signals is well matched and testing results are accurate. If a blood sample contacts the reference electrode R first (e.g. the sample is introduced from the right), the two signals at the working electrode W and the background electrode B are generated at different time points. When the background electrode B makes contact with the blood sample, the reference electrode R has already been completely filled, and at this time, the signal on the reference electrode R has reached the highest intensity (i.e. detection signals have reached the highest intensity). Since the background electrode B is affected by the amount of the blood sample and the time of sample suction, its coverage extent cannot be controlled, causing mismatching of intensity between detection signals and correcting signals and affecting the accuracy of testing results, which can lead to inaccurate testing results of the content of the blood glucose and a waste of test strips.